Beaver Themer is a Beaver Builder extension that allows the page builder to be used outside the main content area of the page. According to the Beaver Themer website:
Beaver Themer lets you create layouts for archive pages, template an entire post type, 404 and search pages, and create parts like headers and footers. Field connections allow you to connect your layouts to the data inside each type of template.
Theme Foundation themes allow Beaver Themer templates to be used in place of the default header and footer. Beaver Themer templates can also be inserted into many more places using the action hooks available all over the theme.
To activate Beaver Themer support uncomment the following line in the includes/settings.php file:
add_theme_support( 'beaver-themer' );